纯方法定义为“不进行任何可见的状态更改”。
如果一个参数为空或抛出异常，我的方法是写一条日志消息。还是纯的吗？写入记录器是可见的变化吗？
这是代码：
/// <summary>
/// Formats with invariant culture - won't throw an exception.
/// </summary>
/// <param name="format">A composite format string.</param>
/// <param name="args">An object array that contains zero or more objects to format.</param>
/// <returns>A copy of format in which the format items have been replaced by the string representation of the corresponding objects in args.</returns>
[SuppressMessage("Microsoft.Globalization", "CA1303:Do not pass literals as localized parameters", MessageId = "CyanCor.Core.Logging.Log.ExceptionPrevent(System.String,System.String,System.Int32,System.String)", Justification = "It is for the logger (riedl)")]
[Pure - yes or no?]
public static string FormatSafe(this string format, params object[] args)
{
if (format == null)
{
Log.ExceptionPrevent("Argument format is null");
return NullFormat;
}
try
{
return string.Format(CultureInfo.InvariantCulture, format, args);
}
catch (ArgumentException exc)
{
Log.Exception(exc);
return format;
}
catch (FormatException exc)
{
Log.Exception(exc);
return format;
}
}